The invention relates generally to drive arrangements for motor vehicles and more specifically to drive arrangements wherein a hydrodynamic torque converter is employed between an engine drive and a hand-shifted gear box.
In a drive arrangement disclosed in German Auslegeschrift No. 1,254,027, clutch seatings connected nonrotatably to a pump impeller are positioned radially outside of seatings fixed to a turbine wheel. The torque converter is used as a starting clutch and the clutch intermediate elements have to be released immediately on starting. The clutch intermediate elements are spring-loaded and thus, in this arrangement, produce rattling noises when the drive engine is switched off because the pump impeller comes to a standstill before the turbine wheel.
In another drive arrangement disclosed in German Offenlegungsschrift No. 3,203,653, a park position located in tne reverse gear gate is provided for a hand shift lever. A special parking gear wheel of the gearbox is brought into a locking position when the hand shift lever is shifted into the park position thereby locking the gearbox outlet shaft.
A clutch device for connecting the gas turbine of an auxiliary engine of a jet aircraft to an air compressor is disclosed in German Offenlegungsschrift No. 2,549,081. In this device, a centrifugal clutch with cylindrical fly-weights used as clutch intermediate elements can be disengaged even under full load and cannot be re-engaged until the shafts concerned are almost at rest. In order to disengage the clutch, tne flyweights emerge from seats located in a clutch ring of the driven clutch half and are radially displaced outwardly into seats formed as corresponding passages in an intermediate ring rotationally connected to the driving clutch half. The flyweights then enter pocket-shaped seats of a selector ring with limited rotational freedom located concentrically outside the intermediate ring when the selector ring is in a corresponding aligned rotational position relative to the intermediate ring.
A friction clutch controlled in a manner depending on rotational speed by fly-weights interacting with engagement and deadpoint springs is described in German Offenlegungsschrift No. 2,437,777. This friction clutch engages at low rotational speeds and disengages at high rotational speeds. In order to achieve a snap effect, the lines of action of the dead-point springs pass through knuckle points when the flyweights are deflected in such a way that a resistant spring force appears before the pivot point is reached and a supporting spring force appears after passing through the pivot point.
Finally, engaging a centrifugal force actuated friction clutch at lower rotational speeds to link a hydrodynamic torque converter and disengaging it at higher rotational speeds is known from German Offenlegungsschrift No. 2,913,694. In order to reduce the occurrence of torsional vibrations when the vehicle is idling, an overrun clutch is connected after a friction clutch in the force path direction. This permits the turbine wheel, which can be brought into drive connection with the gearbox, to overtake the pump impeller connected to the engine drive.
One object of the present invention is to provide a drive arrangement for a motor vehicle having a torque converter whereby a parking brake effect is achievable through shifting of a gearbox into a gear.
Another object is the provision of a parking brake mechanism which engages only when the turbine wheel of the torque converter stops rotating, thereby achieving noiseless engagement.
These and other objects are achieved in accordance with the present invention by the provision of a drive arrangement for a motor vehicle in which a hydrodynamic torque converter is installed in the transmission between an engine and a hand shift gearbox. The torque converter is equipped with a stop clutch which operates in response to the rotational velocity of the torque converter. The clutch engages when the engine and the torque converter are at rest. More specifically, the torque converter comprises a pump impeller and a turbine wheel. Seats are provided in a clutch ring rigidly affixed to the pump impeller of the torque converter and corresponding concentric seats are rigidly affixed to the turbine wheel. The impeller and turbine wheel seats become aligned radially relative to the clutch axis when the engine and torque converter are at rest, thereby allowing flywheel elements within the clutch to operate as clutch intermediate elements which interlock the pump impeller and turbine wheel of the torque converter and thereby prevent relative rotational movement of the gear shaft and the crank shaft. The seats affixed to the turbine wheel are positioned radially outward relative to the clutch ring. This arrangement eliminates the usual rattling noise associated with clutch intermediate elements because the pump impeller clutch ring comes to a stop before the turbine wheel.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.